Concentrate classifiers



' P 1957 P. L. GRIEGERSEN I 2,806,597

'CONCENTRYATE CLASSIFIERS Filed March 18, 1954 3 Sheets-Sheet 1 IN V ENTOR. -Peler 4 'rqerse/z Sept. 17, 1957 Filed March 18. 1954 P. L.GREGERSEN 2,806,597

CONCENTRATE CLASSIFIERS 3 Sheets-Sheet 2 INVENTOR. Pelt)" Greyersen IAtty.

P 17, 19.57 P. L. GREGERSEN 2,806,597

CONCENTRATE CLASSIFIERS 3 Sheets-Sheet 3 Filed March 18. 1954 vINVENTOR.

' P652)" 4. Greyerse'n United This invention relates to concentrateclassifiers adapted for use in classifying ore concentrates andparticularly in the recovery of precious metals such as gold. It is theprincipal purpose of my invention to provide a device of this characterwith means whereby the classification of the material according to sizeis carried on efliciently and those over size particles of the extremelyheavy precious materials may also be collected as nuggets without havingto go back to the regrinding with other over size particles.

The nature and advantages of my invention will appear more fully fromthe following description and the accompanying drawings wherein apreferred form of the invention is shown. It should be understood,however, that the drawings and description are illustrative only and arenot intended to limit the invention except insofar as it is limited bythe claims.

In the drawings:

Figure 1 is a somewhat diagrammatic view in side elevation of theclassifier showing the hopper from which the material is fed to theclassifier and the general construction of the classifier unit itself;

Figure 2 is a longitudinal sectional View taken substantially on theline 2-2 of Figure 1;

Figure 3 is a sectional view taken on the line 3--3 of Figure 2;

Figure 4 is a fragmentary sectional view taken on the line 4-4; ofFigure 3;

Figure 5 is a fragmentary sectional view taken substantially on the line55 of Figure 3; and

Figure 6 is an enlarged fragmentary sectional view taken on the line 6-6of Figure 2.

Referring now in detail to the drawings, my invention is shown asembodied in a classifier wherein the concentrates to be classified arefed from the hopper 10. A water supply conduit 9 is used to supply waterto the concentrate as needed. The hopper 10 has a discharge spout 11which extends into a classifier screen unit 12. The unit 12 is supportedon a suitable framework 13 in a tank 14. The over size material passingthrough the unit 12 is collected in a portion 15 of the tank 14, whilethe smaller size material is collected in the portion 16 of the tank.Suitable conveyors indicated at 17 and 18 are utilized to draw off thecollected material from the tank portions 15 and 16. My invention isparticularly concerned with the construction of the unit 12 and will bedescribed in detail hereinafter.

The classifier unit 12 utilizes a plurality of screens 19, 20, and 21,all of which are conical in shape. The inner screen 21 is the coarsescreen. The intermediate screen is of finer mesh and the outer screen 12is of still finer mesh. For example, the inner screen 21 may be inchmesh, the screen 211 may be inch mesh and the screen 19 /8 inch mesh.Material of more than /a inch size will ride through the screen 21 andbe discharged at its larger end. The material between inch and inchpasses through the screen 21 along with the finer material of less than/4 inch size. The screen 2-41 retains the par- Patent "ice ticlesbetween A and inch size and carries them to discharge at its larger end.The remainder of the material passes through the screen 2% to the screen19 which carries over the material of more than inch size while thefiner material passes through the screen and falls into the section 16of the tank 14. All of the over size particles retained on the screen 21pass through a collecting ring 22 and are kept out of the collectingring by an extended portion on the screen 21.

The collecting ring 22 serves the dual purpose of mounting the largeends of the screens 19, 20 and 21 and of providing a pocket 23 forsegregating extremely heavy particles of the material being classifiedand retaining these particles while permitting the lighter particlesdischarged over the screens 19 and 20 to pass through the ring 22 to thecompartment 15 of the tank 14. The ring 22 as shown, comprises an outerconical wall 24, a flange 25 and an inner conical portion 26. Theportion 24 is joined to a rim portion 27 which extends inwardly to amounting flange 28 for the outer screen 19. The portion 26 has a radialflange 26a at its smaller end which extends outwardly. The rim portion27 has a conical flange 29 which tapers inwardly and is spaced from theflange 28 at its inner end. This construction provides the channel 23with a tortuous entrance passage to restrict the flow of material intothe chamber 23. The rim portion 27 terminates at the mounting flange 28.Four spokes 30 arranged ninety degrees apart, support a hub 31 at thecenter of the ring 22 for mounting a supporting shaft 32.

The ring 22 has a plurality of clean out apertures 33 in the rim portion27. These apertures are normally closed by cover screens 34 held inplace by plates 35 that are fastened to the portion 27 by screws 36. Thechamber 23 will gradually fill up with the heaviest precious metalparticles, such as gold nuggets, and these are removed periodically bydetaching screens 34.

The screen 20 is notched at its large end to fit on the tapered portions30a of the spokes 30 against a shoulder 37 on each spoke. Thisconstruction serves to locate the screen 20 at the proper space from theouter screen 19 which is fitted over the flange 28.

The mounting of the inner screen 21 which is subjected to the load ofall the material entering the classifier, is accomplished by notchingthe screen 21 as indicated at 38 to receive each spoke 30 of the ring22. The screen 21 extends beyond the spokes far enough to overlap theconical portion 26 of the ring so that material on the screen 21 doesnot fall upon the passage 39 between the rim portion 27 and the smallerend of the cone shaped portion 26. A solid metal ring 40 is fitted onthe free end of the screen 21 that extends beyond the spokes 30. Thisring is notched at 41 to receive the bevelled portions 42 on the spokes30. It is secured to the screen 21 by screws shown at 43. The beveledportions 42 of the spokes 30 are terminated just inside the ring 40 soas to provide a guide to position the ring 46 and the screen 21. Ashoulder 44 is also provided on each spoke just inside the screen 21 toposition the screen.

At the other end of the classifier unit 12, means are provided formounting the screens and centering them about the shaft'32. 1 The meanscomprise a casting 45 which has an outer flange portion 46 to receivethe screen 12. This casting also has a raised rib 47 spaced inwardlyfrom the flange 46 to fit over the small end of the screen 20 andsupport it in position. Spaced inwardly from the rib 47 are fourL-shaped spokes 48 formed on the casting 45. These spokes have theirinner ends joined by a hub 49 for the shaft 32. The small end of thescreen 21 fits around the spokes 48. The shaft 32 extends through thecasting ring 45 and through the bottom of the spout 11 where it issupported by a bearing 50. The spout 11 is formed to fit over the shaft32 so that the material entering the classifier unit 12 flows on bothsides of the shaft. The casting 45 and the collector ring 22 are heldagainst the screens 19, 20, and 21, by four bolts 51. The bolts 51extend through apertures in the casting 45 and through apertures in thefour spokes 30 of the collector ring 22. Nuts 52 are threaded on eachend of each bolt 51 to hold the casting 45 and the collector ring 22together.

When the shaft 32 is rotated, the material fed into the unit 12 is movedalong the screens to their lower ends and thus classified according tosize. Generally the liquid level within the tank 14 is high enough tosubmerge the lower portions of the screens and facilitate the washingand separation of the concentrates. The ring 22 receives the materialfrom the screens 19 and 20 so that any particles of the heavier preciousmetals such as gold nuggets, have an opportunity to supplant the lighterrock particles in passing over the inner edge of the cone shaped portion26. These particles work their way into the chamber 23 and are collectedthere for removal at intervals.

It is believed that the nature and advantages of my invention will beclear from the foregoing description.

Having thus described my invention, I claim:

1. A classifier for precious metal ore particles comprising a framework,a screen unit on said framework, said screen unit comprising a pluralityof concentric conical screens of different sizes arranged on ahorizontal axis, one within another in spaced relation to each other,the outer screen being of the finest mesh and each of the other screensbeing coarser than the one outside of it, end supports holding saidscreens in spaced concentric relation, shaft means on the frameworkmounting said end supports for rotation, a hollow collecting ringjoining the large end of said outer screen and having an annularrestricted inwardly facing inlet opening to the interior thereof, acrosswhich the particles retained on said outer screen must pass in leavingthe screen unit.

2. A classifier for precious metal ore particles comprising a framework,a screen unit on said framework, said screen unit comprising a pluralityof concentric conical screens of different sizes arranged on ahorizontal axis, one within another in spaced relation to each other,the outer screen being of the finest mesh and each of the other screensbeing coarser than the one outside of it, end supports holding saidscreens in spaced concentric relation, means on the large end of theinner screen projecting outwardly beyond the adjacent end support tocarry large particles retained on the inner screen outwardly beyond theparticles retained on the other screens, shaft means on the frameworkmounting said end supports for rotation, a hollow collecting ringjoining the large end of said outer screen and having an annularrestricted inwardly facing inlet opening to the interior thereof, acrosswhich the particles retained on said outer screen must pass in leavingthe screen unit.

3. A classifier for precious metal ore particles comprising a framework,a screen unit on said framework, said screen unit comprising a pluralityof concentric conical screens of different sizes arranged on ahorizontal axis, one within another in spaced relation to each other,the outer screen being of the finest mesh and each of the other screensbeing coarser than the one outside of it, end supports holding saidscreens in spaced concentric relation, shaft means on the frameworkmounting said end supports for rotation, a hollow collecting ringjoining the large end of said outer screen and having an annularrestricted inwardly facing inlet opening to the interior thereof, acrosswhich the particles retained on said outer screen must pass in leavingthe screen unit, and said ring having screened outlets from the interiorthereof outside the outer screen.

4. A classifier for precious metal ore particles comprising a framework,a screen unit on said framework, said screen unit comprising a pluralityof concentric conical screens of different sizes arranged on ahorizontal axis, one within another in spaced relation to each other,the outer screen being of the finest mesh and each of the other screensbeing coarser than the one outside of it, end supports holding saidscreens in spaced concentric relation, shaft means on the frameworkmounting said end supports for rotation, a hollow collecting ringjoining the large end of said outer screen and having an annularrestricted inwardly facing inlet opening to the interior thereof, acrosswhich the particles retained on said outer screen must pass in leavingthe screen unit, said ring having a plurality of circumferentiallyspaced outlet openings on the exterior thereof, and removable closuresfor said openings.

5. A classifier for precious mineral ore particles comprising aframework, a screen unit on said framework comprising a plurality ofconcentric screens of different sizes arranged on a common axis onewithin another in spaced relation to each other, the outer screen beingof the finest mesh and each of the other screens being coarser than theone outside of it, end supports holding said screens in spacedconcentric relation, shaft means on the framework mounting said endsupports for rotation, means at one end of said unit to deliverparticles to be screened upon the inner screen, a hollow collecting ringat the other end of said unit fixed to the outer screen, said hollowring having an annular restricted inwardly facing inlet opening to theinterior thereof across which the particles retained on the outer screenmust pass.

6. A classifier for precious mineral ore particles comprising aframework, a screen unit on said frame work comprising a plurality ofconcentric screens of different sizes arranged on a common axis onewithin another in spaced relation to each other, the outer screen beingof the finest mesh and each of the other screens being coarser than theone outside of it, end supports holding said screens in spacedconcentric relation, shaft means on the framework mounting said endsupports for rotation, means at one end of said unit to deliverparticles to be screened upon the inner screen, a ring at the other endof the unit, the end supports at said other end having spokes joined tothe ring, the ring having a flange receiving the outer screen, theinnermost screen extending past said spokes and having notches thereinreceiving said spokes and a solid ring joining those parts of theinnermost screen between the notches that extend beyond the spokestogether.

References Cited in the file of this patent UNITED STATES PATENTS471,322 Wyman Mar. 22, 1892 666,050 Gray Ian. 15, 1901 FOREIGN PATENTS11,455 Great Britain May 9, 1910

